1. Field of the Invention
The present invention relates to a continuous casting apparatus for molten metal and, particularly, to a continuous casting apparatus which permits stabilizing the level of the molten metal during continuous casting, improving the surface properties of the continuous cast slab, and making the casting speed high.
2. Description of the Related Art
In the continuous casting technology for molten metal, in order to achieve stabilization of the level of the molten metal, smoothing of continuous cast slabs and high speed continuous casting, various continuous casting apparatuses and methods of continuous casting have currently been disclosed. The continuous casting apparatus disclosed in Japanese Unexamined Patent Publication (Kokai) No. 5-15949 (Japanese Patent No. 2611559) is equipped with a metal-made cooling mold having a water cooling structure built-in and a conducting coil which is wound around the segments of the mold and which passes a high-frequency current, for the purpose of significantly curving the meniscus portion of the molten metal by the conducting coil. The mold of the continuous casting apparatus comprises segments having a plurality of slits dividing the mold and penetrating or not penetrating the top end of the mold; the lower end of the segments is in an integrated form with the mold. Moreover, a path for water cooling is bored through the interior of each segment.
Japanese Unexamined Patent Publication (Kokai) No. 7-204787 discloses a continuous casting apparatus for metal equipped with a metal-made cooling mold having a water cooling structure built-in and a plurality of slits, and a conducting coil which is wound around the mold and which passes a high-frequency current for the purpose of significantly curving the meniscus portion of the molten metal by the conducting coil. Moreover, Japanese Unexamined Patent Publication (Kokai) No. 10-156489. discloses an inner water cooling type mold wherein the top end is divided by a plurality of slits extended in the casting direction, the lower end of the mold is in an integrated form with the mold, and segments capable of being cooled internally occupy the upper side of the mold. Deformation of the mold equipped with a high-frequency conducting coil is prevented by providing a flange in the upper portion of the mold. Japanese Unexamined Patent Publication (Kokai) No. 4-178247 discloses a process of continuous casting with a mold the wall of which is provided with slits at given intervals and around which an electromagnetic coil is wound to form an electromagnetic field. Japanese Unexamined Patent Publication (Kokai) No. 6-277803 discloses a process of continuous casting with a casting mold equipped with a high-frequency conducting coil wound around the periphery of the mold provided with a plurality of slits, and a magnet for imparting a static magnetic field crossing the casting direction at right angles. Japanese Unexamined Patent Publication (Kokai) No. 52-134817 discloses a casting process comprising imparting an electromagnetic force of about 50 to 6,000 Gauss in a pulse form to molten metal. Moreover, Japanese Unexamined Patent Publication (Kokai) No. 2-274351 discloses a method of imparting low-frequency vibration, while Japanese Unexamined Patent Publication (Kokai) No. 5-285598 discloses a method of imparting high-frequency electromagnetic vibration. Japanese Unexamined Patent Publication (Kokai) No. 7-148554 discloses a continuous casting apparatus provided with an electromagnetic coil wound around divided mold segments formed with slits which decline toward the casting direction.